CA1162584A - Illumination system for microfilm printer - Google Patents

Illumination system for microfilm printer

Info

Publication number
CA1162584A
CA1162584A CA000372395A CA372395A CA1162584A CA 1162584 A CA1162584 A CA 1162584A CA 000372395 A CA000372395 A CA 000372395A CA 372395 A CA372395 A CA 372395A CA 1162584 A CA1162584 A CA 1162584A
Authority
CA
Canada
Prior art keywords
housing
aperture
illumination
microfilm
microimage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000372395A
Other languages
French (fr)
Inventor
James D. Rees
David C. Bliek
George R. Simpson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xerox Corp
Original Assignee
Xerox Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xerox Corp filed Critical Xerox Corp
Application granted granted Critical
Publication of CA1162584A publication Critical patent/CA1162584A/en
Expired legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03BAPPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B27/00Photographic printing apparatus
    • G03B27/32Projection printing apparatus, e.g. enlarger, copying camera
    • G03B27/52Details
    • G03B27/54Lamp housings; Illuminating means
    • G03B27/545Lamp housings; Illuminating means for enlargers

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Light Sources And Details Of Projection-Printing Devices (AREA)
  • Exposure Or Original Feeding In Electrophotography (AREA)
  • Projection-Type Copiers In General (AREA)
  • Combination Of More Than One Step In Electrophotography (AREA)

Abstract

ABSTRACT

The present invention relates to a xerographic printer capable of reproducing microfilm or microfiche images over a broad enlargement range. The printer includes a light housing completely enclosed except for an aperture in the bottom wall. Microfilm or fiche images are successively presented adjacent this aperture.
The walls of the housing are coated with a diffusely reflective material and cause light from a flash illumin-ation source mounted within the housing to diffusely illuminate the surface of the image adjacent the aperture.

Description

1 3 625~4 ILLUMINATION SYSTEM FOR MICROFILM PRINTER

BACKGROUND OF THE INVENTION
This invention relates generally to a ~icrofilm printer and, more particularly, to a flash illumination projection system to be utilized in a xerographic micro-film printer. The recording of data in reduced scale on microfilm has been practiced for many years. The practice has the greatly desirable result of conserving storage space and permitting rapid retrieval and/or reproduction of the recorded material. Whether the data is recorded as microfilm images in strip form or as a group of microfilm images on a single sheet (microfiche), the images must be illuminated with a high intensity light source and projected in enlarged form upon a viewing screen and/or a photosensitive surface.
Prior art xerographic microfilm printing systems have heretofore been limited to the servo scanning type wherein a microfilm image is incrementally scanned and imaged onto a rotating drum type photore-ceptor. The ~erox 970 Microfiche Printing System is one example of this type of prior art printer.
The slit scanning systems have inherent problems associated with their use in printing systems.
The flyback time of the scan illumination system limits the process speed of the system. The imaging onto the photoreceptor is subject to potential distortion caused by vibrations emanating from the moving elements. And, perhaps most importantly, resolution of exposed images may begin to fall off at magnifications above 24X. It would be advantageous to utilize a flash exposure system to reduce or eliminate ~hese problems. A flash exposure system would also result in a lower cost unit because of the less complex imaging and increased reliability. But a ~lash system presents other problems which must be addressed:
~`~ Q~`~

Marks, dirt and scratches present in or on the microimage create a light-scattering effect which causes degradation of copy image quality. An additional problem which would be present in a flash-lamp illumination system is uneven microradiance distribution of the pulsed arc.
The arc exhibits pulse-to-pulse "jitter" creating a non-uniform illumination of the microimage. This non-uniform illumination is projected through the lens and creates a non-uniform exposure at the imaging plane, again adversely effecting copy quality. Another difficulty would be the requirement to utilize different projection lenses to accommodate different microimage sizes.
It is, therefore, an object of an aspect of the present invention to provide a microfilm printer utilizing a flash exposure system~ An object of an aspect of the invention is to incorporate a flash system which will de-emphasize the presence of scratches, dirt, etc. on the microfilm and which will provide a relatively uniform illumination of the microfilm. An object of an aspect of the invention is to provide a compact illumination system which incorporates a zoom lens to provide a wide enough range o~ enlargement values to accommodate present microimage sizes.
SUMMAR~ OF THE INVENTION
Various aspects of the invention are as follows:
An illumination system providing diffusely uniform illumination of a microfilm image comprising:
a housing having a top and bottom surface, the bottom surface adapted to provide an aperture having dimensions at least equal to that of the microfilm image to be reproduced, said housing completely enclosed by side walls joined to said top and bottom surfaces, said housing further characterized by having its interior surfaces completely covered with a high reflectivity material, such that said surfaces are highly diffusely reflective to light incident herein, i 1 62S8~
-2a-means to position a microimage directly beneath said aperture, at least one flash illumination source positioned within said housing, and means to energize said illumination source to produce light flashes which undergo multiple reflections from said coated surfaces to produce a uniformly diffuse illumination of said microimage.
A microfilm flash illumination optical system comprising:
an enclosed light housing having one surface with an aperture therein, means to position a microimage adjacent said aperture, at least one flash illumination source positioned within said housing, and means to energize said illumination source to produce light flashes within said housing to illuminate said microimage.
sy way of added explanation, the present invention is directed to a flash illumination housing which produces a uniformly diffuse illumination of a microfilm image.
In a preferred embodiment, a flash lamp is placed within a completely enclosed housing whose interior walls are coated with a diffusely reflective material. The bottom of the housing has an aperture adjacent on which the microfilm is positioned. The flash illumination undergoes multiple reflections within the housing, resulting in a substantially uniform illumination of the microfilm. The microfilm image is projected onto a photosensitive imaging plane at a desired enlargement by means of a zoom lens.

. "~

1 1 fi2~84 DRAWINGS
The figure is a perspective view of a flash illumination system according to the invention.
DESCRI TION
Referring now to the figure, an illumination system according to the present invention is shown. The illumination source is a flash lamp 8 which is mounted within an enclosed housing generally designated as 10.
Housing 10 has a pair of opposing walls 12, 14, a second pair of opposing walls 16, 18, and a third pair of oppos-ing walls 20, 22, lower wall 22 including an aperture 24.
Wall 22 also has a blocker element 25 mounted therein for purposes to be described more fully below. Zoom lens 26 is positioned under housing 10 in optical alignment with aperture 24. Microfiche aperture card 28 is adapted to be moved along X and Y coordinates so as to bring any of the microimages 28a, b, c, etc. into alignment with aper-ture 24. The microimages may, of course, be inputted in other forms; e.g. 35 mm rolls.
Lamp 8 is of an arc discharge type containing in a preferred embodiment, Xenon gas. The lamp is connected to pulsing circuitry, (not shown) which when activated results in a flash of the required short dura-tion. The interior walls of the cavity have substan-tially diEfuse reflecting surfaces resulting from coating the inte~rior wall surfaces with a high reflectivity (90%
or greater) material. Blocker 25 may be coated with the same reflecting material.
In operation, lamp 8 is pulsed and caused to flash. Light is directed against the cavity walls and the surface of blocker 25. This light undergoes multiple reflections from all interior surfaces and produces a near-uniform diffuse illumination at the aperture 24 and, therefore, at the adjacent surface of the selected micro-image on card 28~ In this type of environment, the arcwander or "jitter" of lamp 8 is completely eliminated as I 1 6~58~

an adverse influence. And, as a second advantage of the diffused light illumination, the presence of scratches, dirt, etc. on the microimage is de-emphasized or softened. The "scattering" effect resulting from the incidence of specular light is greatly reduced since the incident light is now impinging at angles closer to the parallel plane in which the scratches, dirt, etc. lie.
The illuminated image presented beneath aperture 24 is projected at a desired magnification by zoom lens 26, in optical alignment wiih the aperture, onto a flat moving photosensitive image plane 30. The projected ima~e selectively discharges the photosensi-tive sheet resulting in formation of a latent electrostatic image thereon. Image plane 30 is continually moved in timed relation with the pulsing of lamp 8 and advancement of successive microfiche images to sequentially expose successive surfaces of the plane.
The purpose of blocker element 25 is to prevent direct light from lamp 8 from striking aperture 24. The blocker is, therefore, of a width and length sufficient to accomplish this purpose and consistent with the physical dimensions of the lamp. The location of the blocker could be varied: for example, the blocker could be mounted beneath the lamp, extending in an upward angle until the ~irect light path from light to aperture is occluded.
In one example, housing 10 consists of a cube
2" x 2" by 2". The interior of the housing is coated with a celanese polyester thermal setting paint #741-13. The dimensions of aperture 24 are 0.4" (1.016cm) x 0.6"
(1.524cm). A Xenon lamp with an input electrical energy of 25 joules was used as the flash source (for microfiche format A7 projection at 33X). Zoom lens 26 is a Vivitar~
35-85 mm f/2.8 auto Variable Focusing lens which provides a capability of projecting from microfiche formats 1 through 7. (These formats are defined in American i :~ 62S8~

National Standards Specification ANSI/NMR MS~-1978).
Positive output copy can be obtained from negative polarity microfilm using well known reversal development techniques. The photorecepto} is o~ the organic type as disclosed in U.S. Patent 4,115,116.
A uniform illumination at the aperture plane is achieved by some loss in system efficiency: i.e. the illumination level is greater than that required for a specular illumination system. However, housing 10 functions approximately as an integrating sphere and hence is beneficiary to the gain which is a character-istic of such a structure. Basically, the theory of the optical integrating sphere is relatively straight forward and can be explained with a simple example. First, consider a point source of radiarlt energy which is irradiating an elemental surface at some given distance from the source. Let the irradiation incident upon the surface be of some magnitude (Ho)~ If, without changing the intensity of the source or the distance that the elemental surface is positioned from the source, the source is now enclosed within the spherical reflector upon which the elemental surface falls, a resulting new irradiance (~) at the elemental surface is produced.
This new irradiance is a function of the reflectivity of ~5 the inside surface of the sphere. If the reflectivity is a function of wavelength, the average reflectivity taken over the emissive bandwidth of the source can be used to find this new irradiance. Multiple reflections inside the sphere have now greatly increased the irradiance at the elemental surface and a gain factor, that is, the ratio of H to Ho, also becomes a function of the average reflectivity of the sphere. The housing 10 being an almost totally enclosed reflective cavity, conforms to the above principle.
While the Figure showed the aperture 24 approx-imately equal to the microimage advanced beneath, smaller I16~5~1 images can be projected consistent with the principles of the invention. For slightly smaller images, the opaque portions surrounding each image will block unwanted light from entering the lens. For much smaller images wherein 5 portions of adjacent images would enter within the edges of the aperture, a field stop beneath the aperture or at the imaging plane may be required.
The invention can also be practiced in the context of a microfilm printer with some design changes 10 which can be made by those skilled in the art. The aperture 24 would be enlarged and the magnification range would not be as great.
Lamps other than a Xenon flash type may be used and other lamp mounting locations within the housing may be chosen. And while a single lamp has been shown, the techniques of the present invention are equally applicable to a multi-lamp arrangement. Although a zoom lens has been shown to be the preferred focusing and enlarging element, the invention can also be practiced by selecting the appropriate fixed focus lens for the micro~
image size to be reproduced.

Claims (8)

WHAT IS CLAIMED IS:
1. An illumination system providing diffusely uniform illumination of a microfilm image comprising:
a housing having a top and bottom surface, the bottom surface adapted to provide an aperture having dimensions at least equal to that of the microfilm image to be reproduced, said housing completely enclosed by side walls joined to said top and bottom surfaces, said housing further characterized by having its interior surfaces completely covered with a high reflectivity material, such that said surfaces are highly diffusely reflective to light incident herein, means to position a microimage directly beneath said aperture, at least one flash illumination source positioned within said housing, and means to energize said illumination source to produce light flashes which undergo multiple reflections from said coated surfaces to produce a uniformly diffuse illumination of said microimage.
2. Illumination system of claim 1 further comprising a blocking element positioned between the illumination source and the aperture and of sufficient length and width to prevent direct illumination from reacting any portion of the aperture.
3. Illumination system of claim 2 wherein the blocking element is coated with a high reflectivity material.
4. The illumination system of claim 1 wherein said housing has a configuration approximating a cube.
5. A microfilm printer comprising:
a housing having a top and bottom surface, the bottom surface adapted to provide an aperture having dimensions at least equal to that of the microfilm image to be reproduced, said housing completely enclosed by side walls joined to said top and bottom surfaces, said housing further characterized by having its interior surfaces completely covered with a high reflectivity material, such that said surfaces are highly diffusely reflective to light incident thereon, means to position a microimage directly beneath said aperture, at least one flash illumination source posi-tioned within said housing, means to energize said illumination source to produce light flashes which undergo multiple reflections from said coated surfaces to produce a uniformly diffuse illumination of said microimage, and optical means for projecting an enlarged image of said microimage positioned beneath said aperture onto a photosensitive surface.
6. The microfilm printer of claim 5 wherein said optical means is a zoom lens having a capability of projecting images at enlargements of 8X to 40X.
7. The printer of claim 5 wherein said images are microfiche images.
8. A microfilm flash illumination optical system comprising:
an enclosed light housing having one surface with an aperture therein, means to position a microimage adjacent said aperture, at least one flash illumination source posi-tioned within said housing, and means to energize said illumination source to produce light flashes within said housing to illuminate said microimage.
CA000372395A 1980-04-09 1981-03-05 Illumination system for microfilm printer Expired CA1162584A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US138,767 1980-04-09
US06/138,767 US4329045A (en) 1980-04-09 1980-04-09 Illumination system for microfilm printer

Publications (1)

Publication Number Publication Date
CA1162584A true CA1162584A (en) 1984-02-21

Family

ID=22483552

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000372395A Expired CA1162584A (en) 1980-04-09 1981-03-05 Illumination system for microfilm printer

Country Status (4)

Country Link
US (1) US4329045A (en)
EP (1) EP0037733A1 (en)
JP (1) JPS56165136A (en)
CA (1) CA1162584A (en)

Families Citing this family (3)

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Publication number Priority date Publication date Assignee Title
US4415958A (en) * 1981-05-21 1983-11-15 Polaroid Corporation Device for illuminating transparencies
US4466734A (en) * 1982-04-28 1984-08-21 Xerox Corporation Compact full frame illumination and imaging system for a photocopier
BE900890A (en) * 1984-10-24 1985-04-24 Vanhauwaert Luc METHOD AND APPARATUS FOR MULTIPLY REPRODUCING A SAME TRANSPARENT IMAGE.

Family Cites Families (22)

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DE497560C (en) * 1926-07-26 1930-05-15 Fr Cinechromatique Procedes R Device for obtaining positive film strips by copying positive original film strips by the projection method
US3521949A (en) * 1967-09-21 1970-07-28 Data Reproduction Systems Small microfilm reader
US3529129A (en) * 1968-02-23 1970-09-15 Xerox Corp Reflection type flash fuser
US3498715A (en) * 1968-04-22 1970-03-03 Polaroid Corp Illumination system for document copier
US3510221A (en) * 1968-08-26 1970-05-05 Opti Lume Corp Method of photographic reproduction
US3704946A (en) * 1969-02-20 1972-12-05 Opt Omechanisms Inc Microcircuit art generating means
US3697177A (en) * 1970-06-26 1972-10-10 Addressograph Multigraph Illuminating system for a copying machine
JPS5543377Y2 (en) * 1971-09-15 1980-10-13
US3884570A (en) * 1972-01-03 1975-05-20 Personal Communications Inc Reader for reflective background microrecords
JPS5511664Y2 (en) * 1972-06-08 1980-03-13
US3814514A (en) * 1972-09-06 1974-06-04 Xerox Corp Microform projection and viewer apparatus
US4072416A (en) * 1972-09-25 1978-02-07 Izon Corporation Optical scanning system for reading micro-image records
IT968556B (en) * 1972-10-03 1974-03-20 Durst Ag MAGNIFYING DEVICE FOR USE IN A DAYLIGHT ILLUMINATED ENVIRONMENT
US3988064A (en) * 1973-11-13 1976-10-26 Canon Kabushiki Kaisha Reader-printer
US4023903A (en) * 1975-08-11 1977-05-17 Bell & Howell Company Light composer for providing even field illumination and diffuse light
DE2555695A1 (en) * 1975-12-11 1977-06-16 Baum Elektrophysik Gmbh System for production of photographic copies - has series of flash discharge tubes operating independently and adjustable within certain spectral ranges
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CA1079553A (en) * 1976-12-16 1980-06-17 Microvue Products Inc. Front projection type microfiche reader
IT1089585B (en) * 1977-12-01 1985-06-18 Durst Fabbrica Macchine Ed App EQUIPMENT FOR PHOTO ENLARGEMENT USABLE IN AN ILLUMINATED ENVIRONMENT
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BR7907859A (en) * 1979-02-26 1980-09-16 Xerox Corp INSTANT LIGHTING SYSTEM ("FLASH") FULL IMAGE FOR DOCUMENT COPIER MACHINE

Also Published As

Publication number Publication date
EP0037733A1 (en) 1981-10-14
US4329045A (en) 1982-05-11
JPS56165136A (en) 1981-12-18

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